The present invention relates to an air guide box and in particular to an air guide box of a heating, air conditioning and/or ventilation system of a motor vehicle.
In general, in such an air guide box, there are provided at least one air treatment device which may for example be the evaporator of an air conditioning unit, a heating body that can be supplied with engine coolant, an electrical heating appliance or the like. To allow the air which is to be diffused into a vehicle cabin to be adjusted to suit the user, some of the air is usually guided through the air treatment device while some more may be guided past the air treatment device.
In recent years, there has been an increasing desire to be able to have several different air conditioning zones in a vehicle, for example a front air conditioning zone and a rear air conditioning zone or also a separation between the left- and right-hand halves of the vehicle, ranging as far as a combination of the abovementioned two concepts, which is four-zone air conditioning. In order to be able to make such different air conditioning zones available within a vehicle, it has been proposed that outlet paths separated from one another be provided, for example one outlet path for the front part and one outlet path for the rear part, the general trend being for the air conditioning of the front part to take priority, so that, at least in extreme situations, such as the event that there is mist on the windshield, sufficient air conditioning can be guaranteed. As a result, it has hitherto been necessary, in a mixing chamber in which the air treated by means of the air treatment device and the untreated air can be mixed, to provide an air duct which forks laterally and can guide air past the air guide box proper as far as the rear part of the vehicle. This added part does not, on the one hand, allow any independent adjustment of the front part and of the rear part and, on the other hand, requires additional build volume, which is not available most of the time in motor vehicles. The problem of the limited build volume is all the more serious if, as the Applicant company has tried to do, a hot air duct and a cold air duct are provided individually for the rear part, which ducts have both to be guided past the air guide box section for the front part.
Considering these facts, there is a need for an improved air guide box which, for a small required build volume, makes it possible, on the one hand, to, as desired and satisfactorily, supply all the air conditioning zones or just some air conditioning zones satisfactorily with treated air and/or untreated air.
According to the invention, this objective is achieved using an air guide box which has the characteristics of claim 1. Preferred improvements are defined in the dependent claims.
In particular, the invention proposes an air guide box, particularly for a heating, air conditioning and/or ventilation system of a motor vehicle, in which there are provided at least one air treatment device, at least one air path extending across the air treatment device, and at least one air path bypassing the air treatment device and at least two outlet paths. The invention in this context makes provision for the various paths to open into a space in such a way that each time an outlet path finds itself essentially facing one of the other paths, a device that can move about an axis being arranged in this space, which device has an air guiding element in the form of a duct and, in defined positions, provides an air passage with practically no pressure drops between two paths facing each other and an air passage subject to pressure drops between other paths facing each other.
In other words, the invention makes it possible to use one and the same space to guide the air in two different directions, by causing the device to pivot about an axis which, for example, is centered, or may be offset. In one of the defined positions, a configuration of one duct in another is thus provided so that these ducts run essentially in parallel and thus allow a maximum air throughput, for example in the deicing mode, whereas in another defined position, a passage one inside the other of two air streams which are disconnected form one another is possible, it being possible for the two directions of flow to be, for example, at right angles to one another. In the second scenario mentioned, a passage practically free of pressure drops is thus possible in the inner duct, which is defined by the air guiding element in the form of a duct, from, for example, the air treatment device as far, for example, the rear part of the vehicle, while the supply of fresh air to the front part is subject to a certain pressure drop, caused by the presence of the air guiding device in the form of a duct transversely to the direction of flow toward the front outlets of the flow.
Because of the possibility of defining two flow paths one inside the other, at least partially uncoupled from one another, it is possible to obtain particularly short routes for the air to take, so that the heat and/or pressure drops can be minimized even further.
Advantageously, there is isolating engagement in at least one position between the air guiding element in the form of a duct and at least one path, particularly with respect to two paths facing one another. Thus, for example, a continuous air path may be formed between the air treatment device and the rear part, so that a defined quantity of treated air can be diffused into the rear part independently of the technical air conditioning settings of the front part.
In the configuration in which the two air paths cross, to make it possible to use the air originating both from the air path running across the air treatment device and the air path bypassing the air treatment device, the air guiding element in the form of a duct is advantageously provided with an opening which allows the air to fork out of the passage subject to a pressure drop.
The element for guiding the air in the form of a duct may preferably have at least two compartments, at least one of which may be closed, except for the ends. For example, it would thus be possible, in the case where the air treatment device was a heating body, to produce a hot air path defined as far as the rear region, which is flanked by another path which can be supplied with air which is cooler beside the heated air, which is thus branched from the passage subject to a pressure drop.
Advantageously, the cross section of the air guiding element in the form of a duct is practically constant, but nonetheless has at least no significant narrowing which could lead to a pressure drop.
From the point of view of the art of fluid mechanics, it may be advantageous for the air guiding element in the form of a duct to be produced with a curvature, so that it can, for example, in a defined position, allow air to be deflected upward, and in another defined position, allow air to be deflected downward.
In the preferred form of the embodiment, the device which can move about an axis comprises means for blocking at least one path, particularly two paths facing one another in at least one of the defined positions. In this way, it is, for example, possible to prevent air from reaching the rear part, something which is desirable in particular in situations in which the maximum amount of air is required in the front part.
Advantageously, the aforementioned means may be produced as one piece with the air guiding element in the form of a duct and form therewith for example an essentially cylindrical body. If an at least partial double wall is thus provided, the quality of the flow through the device can be improved for arbitrary defined positions and intermediate positions.
The width of the air guiding element in the form of a duct or also of the device which can move about the axis has advantageously to be essentially equal, in the direction of the axis, to the width of at least one path, particularly of a pair of paths facing one another.
Finally, it is preferable for the width of the air guiding element in the form of a duct or of the device which can rotate about the axis in the direction of the axis, to correspond essentially to between 15% and 85%, particularly between 20% and 40%, of the width of a path, particularly of a pair of paths facing each other, the range from 20% to 40% being particularly appropriate for the case where one of the air outlet paths involved is designed for the space at the back or the space for the feet in a vehicle. In other applications, for example when the device which can move is arranged in any arbitrary mixing chamber of the installation, such as the one feeding the dashboard diffusers and the windshield diffusers, another range from 50% to 70% may be anticipated. In this context, it should also be pointed out that the direction in which the device can be moved can range to both essentially horizontally, vertically or also at an angle. Furthermore, the term xe2x80x9cwidthxe2x80x9d must also be understood as meaning a sum of widths, for example when two ducts are arranged spaced apart. In the case of two spaced-apart ducts, these could range from closely side by side out to the widest path edges, it being possible for a wall of the duct or ducts also to be formed by the box itself.
Keeping with the given ratios, it is possible to guarantee that enough air can pass past the air guiding element in the form of a duct in at least one defined position to supply the air conditioning zone which is not supplied with air without pressure drop which crosses this air flow for example at right angles by interposing the air guiding element in the form of a duct.
To sum up, it is possible to establish that the invention makes it possible, at choice, for minimal space requirements, for two air flows to be able to enter one inside the other whereas, in another scenario, in another defined position, practically the entire flow cross section is available as if, for example, an air duct for the rear part of the vehicle was no longer even present.
It should be mentioned that the teaching according to the invention can also apply to several air paths which cross at one or more points, it being possible for the person skilled in the art also to recognize that, from the point of view of the art of fluid mechanics, downstream in the direction of the flow, of the device which can rotate about the axis, other hot and/or cold air supplies are possible, for example also by means of a conventional butterfly valve.